Electrical control system



March 27; 1945. 2, LA FOREST 2,372,435

ELECTRI CAL CONTROL SYSTEM Filed Sept. 14, 1940 90 cunnem 91 SOURCE Bnvcntor fouz's Z. [a FbFSL Patented Mar. 27, 1945 ELECTRICAL CONTROL SYSTEM Louis .Z. La Forest, Morris Plains, N. J., assignor to Thomas A. Edison,

Incorporated, West Orange, N. J a corporation of New Jersey Application September 14, 1940, Serial N 0. 356,881 3 Claims. (Cl. 177-353) 7 This invention relates to electrical control systems, and more particularly to such systems wherein a plurality of work systems are to be selectively energized.

This application is filed as a continuation in part 2,218,542 dated An object of my invention is to selectively operate a pair of work systems, by currents supplied thereto in common, in a novel and advantageous manner.

Another object is Systems Another object is to provide a pair of work systems selectively operable by currents which are supplied thereto in common and which are Other and allied objects will more fully appear from the following description and the appended claims.

In the description of the invention hereinafter set forth reference is had to the accompanying drawing, wherein the single figure is a schematic diagram of a typical embodiment of the invention.

An important feature of my invention concerns the selective operation of a pair of work systems, to which currents are supplied in common, by the selective supplying of the current at either of two different amplitudes. Such selective operation in its broadest aspect is known;

but my invention contemplates its performance of duration of the respect of duration-the double differentiation permitting considerable choice and very simple arrangements of the work systems, while retainin their intended selective response.

While I intend no unnecessary limitation of my invention in respect of how the differentiation of durations shall be effected, I prefer that this be done in response to the postulated difference of amplitudes. Further, while I intend no unnecessary limitation in respect of where the differentiation of durations shall be efiected, I have preferred to efiec-t it, and will describe an embodiment of my invention in which it is eifected, in one of the two work systems. A typical embodiment of that work system is conveniently first described.

Reference being had to the drawing, thisiwork system will be found designated generally as 24.

two electromagnets 25 and 26 having respective first terminals 25a and 26a; a pole 32 pivoted as at point P and carrying an armature Q arranged for alternate attractions magnets to swing the pole 32 back and forth between two discrete positions; .aload device H" of any desired character, electrical or mechanical, linked to the pole 32 and thereby moved or operated between two positions; and contacts 33 and 34 respectively in series with the second terminals of the electromagnets 25 and 26 and arranged to be alternately contacted by the Through one or othe other of these then occupies, that electromagnet, acting on the As is well understood, an operating system for a work circuit of the'described type may be provided by any suitable current source C having one terminal connected for example to the pole 32 through a conductor 80b, and having its other terminal arranged for alternate connection to electromagnet terminals 25a and 26a for example through conductor 9|, single-pole double-throw switch S1, and respective conductors 85a and 86a. When, as illustrated, pole 84 of switch S1 is touching the switch contact 85, electromagnet 25 will have been last actuated and will have thrown pole 32 and load device l! to their illustrated leftward positions, the electromagnet therefore having become open-circuited at 33 and the electromagnet 26 having been prepared for next pole 84 is moved to touch the contact 86, electromagnet 26 will be actuated and will throw pole 32 and load device Nil to their rightward positions, thus open-circuiting the electromagnet 26 and preparing the electromagnet 25 nected to be supplied with current in common with the work system 24 -for example,

serially interposed in the conductor 8% abovementioned. This electromagnet may be arranged to attract a pivoted arm 97, for example through an armature R secured on that arm, from a leftward position to which the arm may be springbiased, to a rightward position. A load device I92 of any desired character, electrical or mechanical, may be linked to or otherwise associated with the arm 91 and thereby moved or operated between two positions or conditions; assuming the device I02 to comprise an electrical switch, it and the arm and electromagnet wouldconstitute a relay. The combination of electromagnet 95 and arm 91 is readily made undresponsive to any supply of current through the conductor 8% which has actuated the work system 24, in view of the limitation of duration of that supply already discussed. In relay parlance, 96--91 is simply made "slow-acting; and as a non-limitative example of a means of doing this, there has been schematically illustrated as attached to the arm 91 a dash-pot device 99, which may be adjusted to render negligible the movement of arm 91 which can occur during the'limited duration of a current supply which has actuated work system 24.

Thus the limitation of durationis relied on for non-actuation of the work system 95by, or its ngn-response to, a current supply which is in,- tended to actuate the work system 24. On the other hand there may be relied on, for nonactuation of the work system 24 by (or its nonresponse to) a current supply intended to actuate the work system 95, the limitation of amplitude of current supply inherent in the postulated amplitude difierentiation-e. g., while the work system 95 may be arranged to be actuated by a current supply at either of the two amplitudes (assuming that supply to have a suflicient duration), the

work system 24 may be arranged to remain un- BB a will, by reason of actuation. On the other hand, when switch for next actuation. Thus it will be understood that the positionof the pole 84 controls the position or conactuated by current supplied at one (the smaller) of the two amplitudes. Such arrangements will be understood to be readily incorporated by such simple expedients for example as properly establishing the constants of the coils and other parameters of the electromagnet 96 on the one hand and of the electromagnets 25 and 26 on the other.

It will therefore be understood that upon the supply of current at the larger of the two amplitudes there will be actuated the work system 24, but not the work system 95' in view of the limitation of the supply to a duration shorter than required for actuation of 95. On the other hand, upon the supply of current at the smaller of the two amplitudes there will be actuated the work system 95, but not the work system 24 in view of the limitation of the supply to an amplitude smaller than required for actuation of 24. The proper selective actuation of the work systems by the two current supplies thus depends both on the amplitude differentiation and on the duration difierentiation.

In the drawing I have illustrated a typical means for selectively supplying the actuating currents of two'diiierent amplitudes. The switch S1, already described, may be taken as the means for supplying the larger-amplitude current. For the supply of the smaller amplitude current there may be suitably shunted about the switch S1 another switch S3 having a current-limiting resistance 93 in series with it.

The lower-shown extremity of switch S1 of course consists of a pair of contacts and 86, to which the abovementioned shunt circuit 53-93 must be suitably connected. It will be observed that, excepting momentarily upon a throwing of switch S1, the pole 84 of that switch touches that one of the contacts 85 and 85 whose conductor and electromagnet (85(1-25 or Mia-26) is open-circuited (at 33 or 34). To be efiective, however, the shunt circuit S393 should normally be connected to that one of those twoconductors (and electromagnets) which is not open-circuited. Therefore the lower extremity of the shunt circuit 83-93 may be connected to the contacts 85 and B6 (and thus conductors 85a and 96a) through a single-pole double-throw switch S2, whose pole 89 is linked (for example mechanically) to the switch S1 to be thrown concomitantly therewith, but which has its contacts (850 and 860, respectively connected with 85 and 86) arranged oppositely to those of switch S1. Thus in an electrical sense the switch S3 is always thrown oppositely to switch S1; and it renders available, for the passage of current to work system (through 24), that one of the two conductors 85a and 86a which is left uncontacted by switch S1.

While no unexpressed limitation thereto is intended, it may be pointed out that the described embodiment of the invention has an especial utility when one of the work systems is to be kept for relatively long periods in each of its two conditions, or positions of its included load device. In such an instance it is this work system which will preferably be of the general kind typified by 24, the automatic limitation of current supply thereto, upon throw to either position, serving the known function of reducing current consumption, electromagnet overheating, and the like. But at the same time, according to a pertinent aspect of this invention, that auto matic limitation of duration is employed to serve the further function of efiecting the additional differentiation of current supplies which makes possible the selective actuation of a. second work system as well, without increase in the number of conductors between the control point and the work systems. 7

Other uses and utilities will readily suggest themselves to those skilled in the art, as will also many modifications of the disclosed embodiment and of Such modifications may be made without departing from the spirit or scope of the invention.

I claim:

1. In an electrical system including means selectively operable to supply currents of two different amplitudes: the combination of means limiting the duration of the supply of one of said currents; and two current-operable work systems both supplied with said currents throughout their durations, one of said systems being responsive only to the limited-duration supply of 2. In an electrical system including means selectively operable to supply currents of two different amplitudes: the combination or a pair of electromagnets each actuable only by the larger-amplitude current; means with said supply means, whereby each supply of said larger-amplitude current is limited to a substantially momentary supply; and a work system, actuable by the smaller-amplitude current but unactuable by momentary current supply, connected to receive current Louis 2. LA FOREST. 

